1. Field of the Invention
The present invention relates to a method and apparatus for reclaiming dry cleaning fluid and for unclogging dry cleaning fluid filter cartridges which are coupled in a recirculation loop with a machine for dry cleaning clothing.
2. Description of the Prior Art
At present, dry cleaning establishments utilize machines for dry cleaning clothing which employ recirculating dry cleaning fluid. The dry cleaning fluid which is typically employed is perchlorethylene, which is known in the dry cleaning industry as "perk". Perchlorethylene will be referred to herein as "perk". As perk is used in conventional dry cleaning systems, it becomes contaminated in machines for dry cleaning clothing because the contaminants on the clothing become entrained in the perk. For this reason machines for dry cleaning clothing are invariably coupled in a recirculation loop with a filter housing which contains filter cartridges. Contaminated perk from the dry cleaning machine is passed through the filter cartridges, which remove many of the contaminants from the perk by filtration. The filtered perk is then returned to the dry cleaning machine for reuse.
Conventional filter housings are pressurized, tubular hollow vessels of generally cylindrical shape. Each filter housing accommodates various numbers of filter cartridges. Each filter cartridge is an annular structure which employs some fiberous filtration material such as paper. The filter cartridges which are commercially available are approximately thirteen and one-half inches in outer diameter and have central axial openings approximately three inches in diameter. The filter cartridges are approximately eighteen inches in axial length and are separated within the filter housing by annular, felt spacers, which have an outer diameter of approximately six inches.
Perk is introduced into the filter housing at a radial inlet near one end of the housing. The perk travels radially inwardly through the filter cartridges and is withdrawn for recirculation to the machine for dry cleaning clothing through an axial outlet in the filter housing.
As the perk is circulated and recirculated, contaminants build up on the filter cartridges. These contaminants include heavy oils, such as soap, significant amounts of water, and also particulate matter, such as lint. Ultimately, the filter cartridges become clogged and a significant pressure differential develops between the perk inlet and the perk outlet of the filter housing. Naturally, this pressure differential impedes the flow of perk through the filter housing.
In conventional dry cleaning systems, one filter cartridge will last through use in dry cleaning approximately two thousand pounds of clothing. When the filters become clogged it is the standard, conventional practice to remove and discard the filters. The filters are removed through an access hatch at the end of the filter housing opposite the perk inlet and outlet. The filters, as they become contaminated, tend to bulge. Upon removal, the filter cartridges typically rupture. Filter cartridges currently cost about $50.00 a piece, and no system presently exists for salvaging them once they have been used. Also, when filter cartridges are removed they contain about twenty gallons of perk. This perk must be replaced, as must the filter cartridges themselves, each time the filter cartridges are changed. The replacement of the perk represents a significant expense, in addition to the cost of the replacement filter cartridges.
A further problem in dry cleaning fluid filter cartridge replacement which has become increasingly acute is that the clogged filter cartridges, each containing approximately five gallons of perk, represent a form of highly toxic waste. Storage of this toxic waste is difficult, due to the fact that the ruptured filter cartridges leak, and must be encased in rugged disposal containers. Furthermore, as waste disposal sites become filled, and as the long term, adverse effects of toxic waste at waste disposal sites have become increasingly apparent, the disposal of clogged dry cleaning fluid filter cartridges has become increasingly difficult and expensive. Indeed, at present in some geographic areas disposal of contaminated dry cleaning cartridges is prohibited, and dry cleaning establishments are finding it increasingly difficult to arrange for the removal of old filter cartridges from their premises.